In a semiconductor device manufacturing process, plasma etching is performed on an etching target film such as an interlayer insulating film formed on a semiconductor wafer by using a photoresist film as a mask so as to form a predetermined pattern, and then a metal, such as Cu or the like, is buried to thereby form wiring.
Since a fluorine-containing gas is used in the plasma etching process, a fluorine-containing material is attached to the etching tar film, and fluorine also remains inside the etching target film or within a lower wiring. Since the reliability of a semiconductor device is degraded when fluorine remains therein, reducing the residual amount of the fluorine is required.
The fluorine-containing material attached to the etching target film or the like may be removed partly by an ashing treatment or cleaning treatment. However, it is difficult to remove fluorine, which penetrates into a film, through the ashing treatment or the cleaning treatment. In addition, using an etching gas containing another halogen, such as chlorine, may also adversely affect the device considerably. Like the fluorine, it is difficult to remove chlorine or the like, which penetrates into the film.
Additionally, techniques for removing a halogen, such as fluorine, have been known. For example, a technique of removing the halogen by heating a halogen atom adsorption layer or a halogen compound adsorption layer formed on a solid surface within a vacuum apparatus is known. In addition, there is a technique of making a process chamber accommodating a semiconductor substrate to be treated into an ultra-high vacuum, then introducing a small amount of hydrogen gas into the process chamber, and performing a heat-treatment on the semiconductor substrate at a temperature of about 300 degrees C. while maintaining the hydrogen pressure at 10−5 to 10−4 torr. In addition, the procedure of removing residual fluorine contaminant on a metal surface after ashing by exposing the residual fluorine contaminant to NH3/O2 plasma has been used.
However, all the techniques perform a treatment in a gas, which is effective in removing a halogen of a film surface, but it is difficult to effectively remove a halogen which penetrate into the film. In addition, the film may deteriorate when plasma is used, and a low dielectric constant (Low-k) film, which has been recently frequently used as an interlayer insulating film which is an etching target film, is a film to be subjected to halogen removal.